It has become common to print the design of an iris of an eye on the surface of a contact lens so as to change the color of the eyes of one wearing the contact lenses. The colorings that make up the human eye are concentrated in numerous radially extending strands with various shades of color in the strands. In order to have the appearance of a natural eye, the pigments must be applied in narrow radially outwardly extending strands similar to the strands of pigment in the eye.
The inks that apply the pigment to the contact lens may be applied to the outer surface of the lens after the lens is manufactured, or may be printed on the concave inner surface of a mold used to manufacture the lens such that when the lens is withdrawn from the mold, the pigment is already imbedded into the convex outer surface of the lens. To apply a colored ink to the concave surface of a mold used to form a lens, the ink is applied by a compressible print pad having a precisely contoured outer surface that deforms as the pad is compressed against the concave surface so as to apply printing across the entire concave surface of the mold.
The outer surface of a print pad used to apply printing to the concave surface of such a mold must also be highly polished in order that the fine lines of color printing be released from the surface of the pad after the surface of the print pad is withdrawn. A print pad useable for printing the design of an eye to the concave surface of a mold, therefore, must be precisely shaped and have a highly polished outer surface.
The manufacturers of print pads have had difficulty obtaining the degree of polish needed and the precise body contour required for such a print pad. Once manufactured, the print pads are therefore carefully checked to insure that the print pad as manufactured has the desired contour and degree of polish. A very high percentage of the print pads manufactured are discarded as failing to meet the required standards. It is desirable, therefore, to provide a method of uniformly manufacturing print pads that meet very high standards with respect to contour and polish.